As a metal is generally hard, it is used for parts which need a high mechanical strength such as a home electric appliance and a car. Further, since a metal has a metallic luster and good texture, it is also used for every possible article in our daily life. Especially, gold is very popular because it provides a feeling of high quality.
However, a metal is expensive and metal machining is not easy. Therefore, the article which is made of a metal is expensive.
As a means for solving the above-mentioned problems, there are some arts such as a metal plating method and a surface coating method. The metal plating method comprises a step of coating a surface of an article which is made of such as a polymer or a glass, with a thin metal film. The surface coating method comprises a step of coating a surface of an article with a coating material which contains such as small particles and a flaky metal.
In these arts, since an article is made of polymer chemical compound and the surface is covered with a thin metal film or coating material which contains a metal, it is possible to manufacture an article having a metallic luster cheaply.
However, with regard to the above-mentioned metal plating, the material which can be used for surface processing is greatly restricted.
Further, the above-mentioned method has to use a metal. Though the cost of an article which is made by the above-mentioned method is cheaper than an article which is all made of metal, it is ultimately expensive.
Especially, in the above-mentioned coating material which comprises a metal, metal particles will be precipitated by the difference of the specific gravity between a polymer binder and the metal. Accordingly, the coating film has a problem that it may become uneven.
Accordingly, it is thought that if material which has metallic luster exists, the above-mentioned problem will be solved.
And, as prior arts with regard to non-metal material, there are articles which are described in the undermentioned NON-PATENT DOCUMENT 1 and 2.